Why did Unicom send me a short message saying that my mobile phone number has entered the lock-up period and asked me to bring my user card to unlock it within 30 days?

Your mobile phone number should be OCS prepaid package. When the phone bill balance is less than or equal to 0 (due to downtime), the OCS package will enter a 90-day recharge period. During the recharge period, all services (voice, SMS, GPRS, etc. ) cannot be used, and can only be restored after recharging. If there is no recharge during the recharge period, it will enter a 30-day lock-up period. During the lock-up period, you can't recharge and activate yourself. You can only use valid certificates, user cards and mobile phone cards to manually unlock them in the local business hall and recharge them before using them. If it is not activated within the lock-up period, it will be sold out.